Federal courts in New York have been issuing preliminary rulings declaring that Aereo’s service is permitted under copyright law. CBS Corp., however, threatened to file a lawsuit in Boston after Aereo announced plans to start service there next week. The Boston court would not be bound by New York’s rulings.

Aereo says that additional lawsuits would be duplicative and wasteful. To thwart them, Aereo is asking the US District Court in New York to declare outright that its service does not infringe on broadcasters’ copyrights, consistent with the preliminary rulings so far.

The declaration sought would apply to Aereo’s expansion markets, including ­Boston.